1. Field of the Invention
The present invention concerns hydrostatic sterilizers or cookers, and more particularly is directed to apparatus for assembling randomly fed incoming containers into a nested pattern forming one tier, and for loading successively formed tiers into a container carrier or basket which is then transported through the sterilizer to heat-treat the contents of the containers.
2. Description of the Prior Art
The United States patent of Busse, U.S. Pat. No. 2,506,661, issued May 9, 1950, discloses apparatus for loading cans in conjunction with a false-bottom retort crate or basket. The false-bottom plate is elevated within the retort to receive a single file or containers and is tilted to facilitate movement of the containers into a tier substantially the area of the bottom plate. Then, a separator plate is placed on the tier, and the bottom plate is lowered within the retort so that the next layer of containers is placed on the separator plate, and so forth until the retort is filled. This apparatus is relatively slow in operation due to the single file feeding mode, and subjects the containers to considerable handling impacts which can damage or detroy them. The apparatus is not considered to be economically feasible for loading the container baskets of presently used hydrostatic cookers and sterilizers, due to the large capacity and relatively high speed operation of the latter.
One of the foremost commercial disadvantages which is common to container handling and pattern forming mechanisms, such as the Busse device, is that the containers are easily damaged when subjected to mechanical handling, particularly with the aluminum cans and glass containers now in wide use. Some can handling devices, such as pallet loaders which assemble steel cans, employ electro-magnetic lifting devices for transferring an assembled tier of cans, thus eliminating most of the can damaging hazards during the transfer operation. With non-ferrous containers, however, magnetic transfer cannot be employed, and in some prior art can handling devices a relatively high percentage of damage is inevitable because of the mechanical means employed to assemble a group of cans in nested relation to form a unitary charge for stacking or filling, and because of the mechanism necessary for moving the filling charge to a container.
Further sources of potential can damage exist in a loading device where incoming cans are arrested on a continuously moving conveying surface to separate the upstream cans from an assembled charge of cans because the conveying surface abrades the arrested cans. This arrangement also inhibits lateral discharge of the assembled can charge where that mode of operation is required. Further, it is common to have the assembled charge of cans closely confined by fixed and/or movable guides while the charge is moved to alignment with the receiving receptacle in order to retain their assembled pattern, so the possibility of can damage exists until the charge is deposited into the receptacle. After the can tiers are deposited in the receptacle with a planar separator panel between adjacent layers, they become partially buoyant in the sterilizer so that the cans at the perimeter of the can charge repeatedly contact the walls of the receptacle and are thus often damaged.
In addition to the Busse patent, supra, other patents of general interest relative to certain individual details of the present loading device are: Tomkins U.S. Pat. No. 2,571,790, issued Oct. 16, 1951, discloses a can arranging apparatus for forming a tier of empty cans in nested relation, and includes an overhead rotor for controlling the movement of selected cans to stagger and nest the adjacent rows of cans.
In the Socke et al. U.S. Pat. No. 2,524,846, issued on Oct. 10, 1950, already assembled tiers of cans are stacked in a bag by apparatus which also places a planar separator panel between adjacent tiers. Each tier is transferred by a vacuum gripping apparatus which engages the upper end of each can. In a later Socke U.S. Pat. No. 2,619,237, issued on Nov. 25, 1952, spaced and staggered rows of cans are transferred as a group to a compacting station where the group is enclosed on three sides and compacted by a pusher that engages the remaining side.
O'Neil U.S. Pat. No. 2,718,313, issued on Sept. 20, 1955, discloses a magazine which deposits a charge of containers, having rows aligned in both directions, onto a plunger which lowers the charge into a chamber where every other row of cans is mechanically shifted so that the assembled groups of cans are nested for packaging or storing.
Bainbridge U.S. Pat. No. 2,959,009, issued on Oct. 28, 1958, discloses a can palletizing machine which includes a pattern forming mechanism for assembling a nested tier of cans. For this purpose, the patentee employs a continuously moving planar conveying surface, and an overhead pattern former having depending pins to arrest a transverse row of incoming cans. All incoming cans are thus retared while the conveyor continues to urge the cans toward the arrested row, the result of which is that the cans seek nested positions so that an assembled group is formed with the transverse rows staggered and nested. The probability of can damage is relatively high because of the coextensive contact of the bottoms of the cans on the conveying surface, and because the overhead pattern forming pins must enter small gaps, between adjacent cans, that only exist if the impositive nesting operation occurs without malfunction.
A machine for stacking cans on pallets is disclosed in the Busse U.S. Pat. No. 2,949,179, issued on Aug. 16, 1960. In the patented machine, longitudinal lane dividers over a conveying surface guide rows of cans to a pattern forming station where a group of nested cans are assembled for subsequent transfer onto a pallet. In order to nest the cans, a complete transverse row of aligned cans is clamped by individual overhead clamps against a stationary support plate. Then, every other longitudinal row of cans of the group thus separated is stopped by an individual stop in front of the leading can, with the result that a nested pattern of assembled cans is formed. After the lane dividers are lifted, a sweep arm pushes the assembled cans unitarily toward the laterally adjacent pallet. In order to retain the pattern of the assembled group of cans, the sweep is of U-shape to embrace three sides of the group. The patented device is considered to be relatively complex in that it requires several compound motions to place various mechanisms into and out of the can paths to prevent interference with other movable parts. This patent and the previously mentioned Busse U.S. Pat. No. 2,506,661 have several structural parts which are similar to those in applicant's improved loader, but lack the basic concept and certain structural features of applicant's mechanism, as will presently be explained. One important object of the present invention, and lacking in the prior art above discussed, is to provide means, apart from the loader, for controlling the assembled, nested group of cans during the transfer or loading operation, and for preventing the cans from later contacting the walls of the container basket into which they are loaded for processing in a hydrostatic sterilizer.